Switch with moving contact makers in the form of spring tongues

ABSTRACT

The present invention concerns a switch, preferably a steering column switch for an automobile, with which both control currents and load currents are to be controlled. The object of the present invention is to mostly prevent soil and scale from forming on the contact surfaces. The present invention achieves this object by transforming the grinding movement of the operating element into a movement of the contact points perpendicular to one another with the help of a mechanical control. Advantageous embodiments involve the design and positioning of the contact points as well as the design of the mechanical control and a method of assembling the switch according to the present invention.

TECHNICAL FIELD

This invention relates to electrical switches and more particularlyrelates to switch contacts formed by spring tongues.

BACKGROUND OF THE INVENTION

For electrical switches for automobiles, it is known that the movablecontact points connected to the operating element can be designed asspring tongues which are stamped out of a contact plate. Such a switchis described, for example, in German Patent No. 4,039,984. With theknown switch, the operating element is shifted parallel to the plane ofthe stationary contacts, so that electrical connection between themovable contacts and the stationary contacts is achieved due todisplacement in the desired order.

One disadvantage of the known switch is that the movable spring tonguesare not attached to the operating element until after the forming of theoperating element. An additional disadvantage of the known switch isthat due to the abrasive movement, the movable contact areas maintaincontact with the insulating compound in which the stationary contactsare embedded as well as the stationary contacts themselves. In addition,during the transition to contacting or separating from a stationarycontact, the contact surface between the moving contact and thestationary contact changes relatively slowly, while at the same time,part of the movable contact remains in contact with the insulatingcompound surrounding the stationary contact. The resulting electric arccauses heating of the surrounding insulating compound and possiblesoiling of contacts, formed due to the insulating compound, is burnedinto the movable contact.

The object of the invention is to improve on the switching performanceof the switch of the known generic type, so that both load currents andcontrol currents can be switched by this switch.

The invention consists in principle of joining the spring tonguestogether through a plastic socket and also anchoring the plastic socketin the switch housing. This prevents a shifting movement parallel to thecontact plane of the stationary contacts. The change in contact closurebetween stationary and movable contacts takes place instead with thehelp of a mechanical control, which is driven by a suitable operationlinkage. In this way it is possible to avoid a transfer of the movablecontacts from the stationary contacts to the insulating compoundsurrounding the stationary contacts, so that soiling of the contacts isprevented, and a clean separation of the contacts from one anotherduring the switching operation is possible. Furthermore, it is possibleto simplify the casting mold of the switch housing, since the plasticsocket with the spring tongues and the housing itself are produced inseparate casting operations. The design of the switch according to thepresent invention also makes it possible to test the contact closure ofthe movable contacts step by step before the anchoring of the plasticsocket in the switch housing, as discussed further below.

According to one preferred embodiment, all contact tongues runningessentially parallel to one another are punched out together in onepunching operation, wherein they are still mechanically connected to oneanother. Then the contact tongues that are connected to one another bywebs are fixed opposite one another by injection of a common plasticholder, and finally, in a third step, the spring tongues areelectrically separated from one another in the desired manner by cuttingthe connecting webs open subsequently.

One disclosed method of connecting the movable contacts to stationaryplug-in connections takes advantage of the fact that the spring tonguesopen into plug-in connections that are molded in one piece and, togetherwith the spring tongues, are punched out of the contact plate. It may bepreferred to strengthen the plug-in connections by designing them ascontact blades which are formed by folding corresponding projections onthe spring tongues. In a preferred embodiment, the plug-in connectionsare anchored in the switch housing at the same time by the engagement ofthe plug-in connections through openings in the switch housing.

To achieve the result that the movable contacts on the contact tonguesestablish contact with the stationary contacts as a result of themovement of an operating element in suitable operating sequence, anotherembodiment of the present invention proposes modification of the radialcam, wherein it is thus possible to change the operating sequence evenwith the same movement curve of the operating element. The presentinvention is particularly suitable for activating the movable contactsby means of an actuating lever of a steering column switch. Through themovement of the actuating lever, the radial cams assigned to theindividual spring tongues act on the spring tongues and thus create thepredetermined contact closure as a function of the position of theactuating lever. If the sequence of contact closure is to be variable asa function of the predetermined positions of the actuating lever, so inanother embodiment of the invention, one need only select the suitableradial cams in order to obtain the desired switch sequence through theposition of the actuating lever.

The design of the actuating lever can be simplified through theintroduction of the radial cam regardless of the design of the actuatinglever. This measure can be used not only with respect to a single springtongue, but also on several or even all spring tongues. To simplify theassembly of the driver rod in the switch, it is proposed in anotherembodiment of the invention that the driver rods be connected to oneanother by parallel plastic spring arms, which are in turn connected toone another. Thus, the totality of all the driver rods serving tooperate a switch are combined in a single component, which simplifiesthe assembly of the switch through the driver rod, since now only thecommon cross piece must be anchored in the switch housing.

The resulting construction essentially looks like a comb, with thedriver rods projecting at right angles to the plane of the comb at theend of the comb teeth. Since the switch housings are to be equippedautomatically with these combs, the teeth of the comb must be preventedfrom becoming entangled in the shipping container. For this purpose,rake-like projections are provided on the comb teeth, extending into theplane of the comb and thus filling up the interspaces between the combteeth. This makes it impossible for the teeth belonging to differentcombs to become entangled.

In order to be able to anchor the spring tongues in the switch housingjointly in one operation, the plastic socket is inserted into a guideopening in the switch housing parallel to the plane of the springtongues. It is thus necessary only to insert the plastic socketautomatically into the switch housing in a first direction perpendicularto the plane of the spring tongues and then engage it with the housingin a second direction perpendicular to the plane of the spring tongues.

To also ensure the creation of terminal contacts on the housing withthis insertion movement of the spring tongues at the same time, theblade shaped plug-in connections extend in the insertion direction ofthe plastic socket. The advantage of such a design is that with theinsertion of the plastic socket into the switch housing, the terminalcontacts are also simultaneously inserted in to the respective openings,so that at the end of the end of the movement of the spring tongues inthe aforementioned direction, the terminal contacts protrude from theswitch housing.

By designing the plastic socket and the cross piece such that theyextend from above in the same direction are inserted in the open switchhousing, automatic assembly of the switch elements is greatlysimplified, and thus can be assembled by the same automatic equipment.

From what has been said, it is apparent that with the present inventioneasy insertion of the aforementioned switch elements into the switchhousing should be possible at the same time. For this purpose certainprocess steps are disclosed; these steps are also used at the same timeto test the movable contacts in their contact position inside theswitch. Therefore, in principle, the method is to insert the plasticsocket provided with the movable contacts into the housing, checking onwhether all the movable contacts are a distance from the respectivestationary contacts in this position. This rules out the possibility ofinserting contact leads, where at least one spring arm in the latterposition reaches the respective stationary contact.

Then the plastic socket with the individual spring tongues is inserted acertain distance, and then one determines whether in this position allthe movable contacts are in contact with the stationary contacts. If oneof the spring tongues is bent so far that no contact is made in thiscondition, then the entire contact lead is not allowed for assembly. Theplastic socket is subsequently engaged in the switch housing in adirection in which the contact pressure of the supported movablecontacts is increased by a certain amount. After carrying out thesesteps, one can be certain that the switch will open and close properlydepending on the position of the respective driver rod.

This method is thus summarized as follows:

1. Assembly step 1 includes the insertion of the plastic socket withsprings/tongues (i.e., the "ZUS spring⃡ or "assembled spring") into thebase plate.

Subsequent testing to determine whether all contacts are still open. Ifa contact is closed, a spring arm must be bent downward.

2. Testing for contact closure includes pressing the ZUS spring adefined distance in the engaged direction.

Then testing is made to determine if for whether all contacts areclosed. If a contact is not closed, a spring arm must be bent upward.

3. Assembly step 2 includes engaging the ZUS spring

The spring arms are prestressed, which creates the contact force.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of the spring tongues joined together by aplastic socket into which the plug-in connections have not yet beeninserted.

FIG. 2 is a rear view of the spring tongues according to FIG. 1 with theplug-in connections inserted.

FIG. 3 is a side view of the spring tongues according to FIG. 1.

FIG. 4 is a view of the spring tongues according to FIG. 3 with unfoldedplug-in connections, which extend perpendicularly to the plane ofobservation.

FIG. 5 is an enlarged view of an actuating lever of a steering columnswitch, which engages a control device for controlling the radial cams.

FIG. 6 is an enlarged view of a switch driver rod, which is acted uponby the relevant radial cam.

FIGS. 7, 8 and 9 illustrate three positions of the spring tongues fortesting the contact closure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows the contact tongues 1, 2, 3, which have the movablecontacts 4, 5, 6 on their resilient ends. The contact tongues arepunched out of a common contact plate 7 and connected with each other bya plastic socket 8. Before extrusion coating of plastic socket 8, thecontact tongues are connected to one another by webs, so that they caneasily be placed in the desired position in the casting mold. Afterextrusion coating, the connecting webs creating unwanted electricalconnections are separated.

It is important for the punched grid according to FIG. 1 that contactlugs 9 through 11 are also molded on the grid at the same time, andafter extrusion coating, they are folded with the plastic socket 8 toform the plug-in connections 12, 13, 14. As indicated by dotted linesinside the plastic socket 8, the contact tongue 1 is electricallyconnected with the two plug-in connections 12, 13, and the two springtongues 2 and 3 are electrically connected to plug-in connection 14.FIG. 3 shows a side view of FIG. 1.

In FIG. 4 the area of the terminal lugs 15 in FIG. 1 is bent at a rightangle to the plane of observation, and at the same time, the plug-inconnections 12 through 14 are inserted according to FIG. 2.

FIGS. 1, 3, and 4 also show a catch strip 16 by means of which theplastic socket 8 with the switch housing can be engaged.

FIG. 7 shows the spring tongue 1 with the movable contact 4 in anenlarged view, where the movable contact 4 is opposite a stationarycontact 17, which is locked on the switch housing. In the position ofthe contact tongue shown in FIG. 9, where the catch strip 16 is engagedin a corresponding recess 18 in the switch housing, the movable contact4 lies on top of the stationary contact 17 so that these two contactsare connected to one another in the starting position of the switch.

Then, to be able to separate contacts 4 and 17 from one another, thecontact end 19 of the spring tongue 1 must be raised against theapparent direction of prestress. This is done by means of a driver rod20, which acts with its driving surface on the contact end 19 of thespring tongue 1.

As FIG. 6 shows, the driver rod 20 passes through a passage 23 in a wallin the switch housing 22. The driver rod here is driven by a radial cam24, which moves past the driver rod 20 in the direction of the doublearrow F on the driver rod 20 at a right angle to the direction ofmovement of the driver rod. The cam carrier 25 is entrained by the endof an actuating lever 26 (see FIG. 5) in the direction of the doublearrow (F) according to FIG. 6, by tilting the actuating lever 26 aroundthe bearing journal 27 within a driver 28 in the switch housing of thesteering column switch. Due to this tilting movement, the cam carrier 25is shifted in the direction of the double arrow F, and thus the radialcam 24 is brought to the intended switch positions on the driver rod 20.The driver 28 can in turn be pivoted about axis A over a bearing hole 29and a bearing journal 30, but the end of the actuating lever 26 isfreely movable in the cam carrier 25 in the swiveling motion.

For the switch according to the present invention, the fastening of thedriver rod is important; three of these driver rods are provided withthe switch described here, but only the two driver rods 20 and 29 can beseen in FIGS. 7 through 9. The three driver rods 20, 29 are eachconnected over a spring arm 31 to a common cross piece 32, where thecross piece 32 with the three spring arms 31 essentially looks like acomb with three teeth, and the driver rods 20, 29 located on theindividual spring arms (teeth) project at right angles to the plane ofthe comb. The driver rods are driven by the cam carrier 25 which isguided in the housing wall by means of its radial cams 24 (see FIGS. 6and 7), where the cam carrier 25 is guided in the direction of thedouble arrow F at a right angle to the plane of observation in FIG. 7.

For the switch according to the present invention, it is conceivable forboth the cam carrier 25 and the cross piece 32 and the plastic socket 8to be inserted from above into appropriate recesses in the switchhousing parallel to the plane of motion F, so that all three elementscan be assembled in the same direction. No problems occur as a result,because in this case the plug-in connections 14 also point in the samedirection and can be guided through corresponding openings in thehousing floor of the switch.

It is especially important for the invention to be sure that the contacttongues 1, 2, 3 do not have any unacceptable deformation. To check onthe correct shaping of the spring tongues 1, 2, and 3, the procedurefollowed is illustrated in FIGS. 7 through 9. As soon as the plasticsocket 8 is shifted to the appropriate opening in the housing wall 22 ofthe switch housing, a suitable continuity check is performed todetermine whether the movable contacts 4, 5, 6 are free of contact withthe respective stationary contacts 17. If this is the case, a test isperformed to determine whether all the movable contacts will haveelectrical contact with the respective stationary contacts 17, if theplastic socket is inserted further by a predetermined amount. If this isthe case, one can be sure that the movable contacts are in fact raisedas desired (see FIG. 7) in the corresponding operation of driver rodsand otherwise are closed.

Next the catch strip 16 corresponding to FIG. 9 is registered in acorresponding catch groove, whereupon it moves a predetermined amount,which leads to a corresponding prestress on the movable contacts 4 withrespect to the stationary contacts 17. Since the plug-in connections 12and 13 are held in the corresponding openings of the switch housing, thespring tongues 1 through 3 are deflected accordingly, so that with aslight shift of the catch strip one can produce a considerable initialspring tension. The essential advantage of the invention consists of thefact that a movement (displacement) in a plane of the operating elementis transformed into a perpendicular movement of the contacts withrespect to one another, so that in this way soiling and materialabrasion are largely prevented. Furthermore, the switch can beautomatically assembled and tested. The complexity of the casting moldfor the switch housing is reduced by the present invention.

What is claimed is:
 1. A switch, comprising:a plurality of movablecontact points, a plurality of springs, wherein each spring isrespectively in connection with one of said plurality of movable contactpoints, a plurality of stationary contact points defined according tothe position of an operating element, wherein said springs aremechanically connected to one another by an extrusion-coated plasticsocket, wherein the plastic socket is held in a stationary position in aswitch housing by a catch engagement; and wherein the movable contactpoints are activated by a mechanical control which acts due to themovement of an operating element and which activates the contact pointsby a shifting movement which is substantially perpendicular to themovement of the contact points.
 2. Switch according to claim 1, whereinthe springs are formed from a punched grid.
 3. Switch according to claim1, wherein the springs include contact paths on ends facing away fromthe movable contact points wherein the contact paths develop in onepiece into the plug-in connections which protrude through correspondingopenings into the switch housing.
 4. Switch according to claim 1,wherein the mechanical control has at least of one radial cam assignedto each one of said springs, whereby the at least one radial cam acts onits associated spring translating a force by way of the operating driverrods.
 5. Switch according to claim 4, wherein the radial cam is indirect communication with an actuating lever of a steering columnswitch.
 6. Switch according to claim 4, wherein the radial cam actstranslating a force by way of a driver rod on the respective spring andthe movement of the driver rod through a guide opening in a switch wallis limited by a stop.
 7. Switch according to claim 6, further includinga plurality of plastic driver rods that move across a plane of thesprings and wherein said plurality of plastic driver rods are connectedto one another by parallel plastic spring arms, which open into a commoncross piece which is anchored in a guide slot in the switch housing. 8.Switch according to claim 7, wherein the plastic arms are provided withparallel projections parallel to one another, essentially in the planeof the plastic arm.
 9. A switch, comprising:a plurality of movablecontact points, a plurality of springs, wherein each spring isrespectively in connection with one of said plurality of movable contactpoints, a plurality of stationary contact points defined according tothe position of an operating element, wherein said springs aremechanically connected to one another by an extrusion-coated plasticsocket, wherein the plastic socket is held in a stationary position in aswitch housing by a catch engagement; and wherein the movable contactpoints are activated by a mechanical control which acts due to themovement of an operating element andwherein the plastic socket isinserted into a guide opening in the switch housing parallel to theplane of the springs and is locked in a catch groove in the switchhousing by a projection which is perpendicular to the plane of thesprings and has undercuts.
 10. Switch according to claim 3, wherein theplug-in connections extend in the insertion direction of the plasticsocket through the respective switch housing openings.
 11. Switchaccording to claim 1, wherein the plastic socket and the cross piece canbe inserted into the switch housing in a direction selected from thegroup of directions consisting of the same assembly direction and theassembly direction wherein the cross piece is engaged perpendicular tothe plane of the plastic socket.
 12. Method of assembling a switch,comprising the steps of:inserting a plastic socket into a housing untilthe movable contact points carried by said plastic socket are oppositestationary contact points in the housing, testing said switch todetermine whether contact points belonging to one another are free ofcontact and provide at least a nominal gap therebetween; inserting theplastic socket further by a predetermined distance by a device andpivoting said plastic socket, and then retesting said switch todetermine whether the respective contact points make contact with oneanother in this position; and finally, inserting the plastic socket intothe housing across the plane of the springs by another predetermineddistance and, locking said housing into position.